Perspectives on Salmon Feed: A Deliberative Assessment of Several Alternative Feed Resources

The future of salmon aquaculture depends on the adoption of alternative feed resources in order to reduce the need for fish meal and fish oil. This may include resources such as species from lower trophic levels, by-products and by-catch from fisheries and aquaculture, animal by-products, plants, genetically modified (GM) plants, nutritionally enhanced GM plants and products from microorganisms and GM microorganisms. Here, we report on a deliberative assessment of these alternative feed resources, involving 18 participants from different interest groups within Norwegian salmon aquaculture. The participants defined a broad range of appraisal criteria concerning health and welfare issues, economical issues, environmental issues, and knowledge and social issues. A number of uncertainties, in the form of incomplete knowledge, diverging opinions, and context specific factors were identified when the participants evaluated the alternatives. Our findings support the need for more research on the suitability of alternative feed resources for farmed salmon. Additionally, the study underlines the importance of facilitating deliberative assessments in order to map the plurality of perspectives and explore qualitative aspects of uncertainty. Such initiatives improve the information base upon which decisions on future feed resources for farmed salmon are made.     

Exposure of atoll population to coastal erosion and flooding: a South Tarawa assessment, Kiribati

Atoll countries are particularly vulnerable to coastal hazards in the context of global change, which justifies the interest in population exposure assessments. This paper contributes to addressing this need by assessing the current exposure of the population of two areas of the South Tarawa Urban District (Tarawa Atoll, Republic of Kiribati) to coastal erosion and flooding. The assessment is based on data relating to island morphology (digital terrain models and shoreline change), land use (building extension and coastal works) and environmental changes reconstructed for the 1969–2008 period. The results highlight rapid changes in land use and significant differences in current population exposure to coastal erosion and flooding between and within study sites. Between 1969 and 2007–2008, the built area located less than 20 m from the reference shoreline has increased by a factor of 4.2 at Bairiki and by a factor of 32.2 at Eita–Bangantebure, enhancing population exposure given that land elevation is low (12.6 and 77.4 % <2 m at Bairiki and Eita–Bangantebure, respectively). Nevertheless, in Bairiki, 87.5 % of the built area is currently not exposed to coastal erosion (>20 m from the coastline) and flooding (>1.5 m). Building exposure is higher at Eita–Bangantebure, where 71.3 % of the built area is currently not exposed (using the same criteria), but 17.1 % shows medium to very high levels of exposure, due to very low land elevation (22.3 % of the land area <1.5 m) and shoreline recession. The Eita–Bangantebure case study exemplifies the maladaptive trajectories of change that have been reported in other atoll countries.     

Pesticide uses and transfers in urbanised catchments

An investigation on herbicide uses in two semi-urban catchments was performed simultaneously with sampling campaigns at six stations inside both watersheds from April to July 1998. Urban uses of herbicides exceeded agricultural uses, and transfer coefficients were also higher in urban areas. Therefore, the most used product in urban areas (diuron) was by far the most contaminating product. Householders accounted for 30% of all uses. The highest measured diuron concentration in water surface was 8.7 microg l(-1) due to its use on impervious surfaces. Compared to EEC standards for drinking water production (0.1 microg l(-1)), it is clear that suburban uses of herbicides may severely endanger drinking water production from river water.     

Spatial and time variations of radon-222 concentration in the atmosphere of a dead-end horizontal tunnel

The concentration of radon-222 has been monitored since 1995 in the atmosphere of a 2 m transverse dimension, 128 m long, dead-end horizontal tunnel located in the French Alps, at an altitude of 1600 m. Most of the time, the radon concentration is stable, with an average value ranging from 200 Bq m(-3) near the entrance to about 1000 Bq m(-3) in the most confined section, with an equilibrium factor between radon and its short-lived decay products varying from 0.61 to 0.78. However, radon bursts are repeatedly observed, with amplitudes reaching up to 36 x 10(3) Bq m(-3) and durations varying from one to several weeks, with similar spatial variations along the tunnel as the background concentration. These spatial variations are qualitatively interpreted in terms of natural ventilation. Comparing the radon background concentration with the measured radon exhalation flux at the wall yields an estimate of 8+/-2 x 10(-6) s(-1) (0.03+/-0.007 h(-1)) for the ventilation rate. The hypothesis that the bursts could be due to transient changes in ventilation can be ruled out. Thus, the bursts are the results of transient increased radon exhalation at the walls, that could be due to meteorological effects or possibly combined hydrological and mechanical forcing associated with the water level variations of the nearby Roselend reservoir lake. Such studies are of interest for radiation protection in poorly ventilated underground settings, and, ultimately, for a better understanding of radon exhalation associated with tectonic or volcanic processes.     

Functions of Straw for In Situ Remediation of Acidic Mining Lakes

The addition of straw in combination with Carbokalk, a by-product from the sugar-industry, was successfully used to stimulate microbial alkalinity generation in an acidic mining lake. To get detailed information about functions of straw, anenclosure experiment was carried out. Straw bundles were placedat the sediment surface of an acidic mining lake (ML 111) and thephysiochemical conditions and the microbiology of the sediment-water contact zone were studied. Straw was degraded by anaerobic microorganisms and dissolved organic carbon (DOC) leached from straw bundles. Pigmented flagellates responded to the DOC supply in the water column anda considerable amount of algal carbon was transported to the sediment. Straw addition led to microbial reduction of iron andsulfate in the sediment. Sulfate reduction was observed at a pHof 5.5. The pH, however, was not high enough to precipitate H₂S completely. Thus, some H₂S diffused into the watercolumn, where it was reoxidized. Straw did not create orstabilize an anoxic water body above the sediment. Microbial sulfate reduction and pyrite formation only took place in the sediment,whereas iron reduction also took place in the straw. Straw, however, altered the flow conditions above the sediment surfaceand prevented complete mixing of the profundal water. Straw didnot serve as a substratum for a reactive biofilm. We conclude that the most important function of straw for mining lake remediation is to be a long-term nutrient source for microbialalkalinity generation in the sediment.     

A new method to assess the deformations of internal organs of the abdomen during impact

Objectives: Due to limitations of classic imaging approaches, the internal response of abdominal organs is difficult to observe during an impact. Within the context of impact biomechanics for the protection of the occupant of transports, this could be an issue for human model validation and injury prediction.

Methods: In the current study, a previously developed technique (ultrafast ultrasound imaging) was used as the basis to develop a protocol to observe the internal response of abdominal organs in situ at high imaging rates. The protocol was applied to 3 postmortem human surrogates to observe the liver and the colon during impacts delivered to the abdomen.

Results: The results show the sensitivity of the liver motion to the impact location. Compression of the colon was also quantified and compared to the abdominal compression.

Conclusions: These results illustrate the feasibility of the approach. Further tests and comparisons with simulations are under preparation.     

Effects of chronic external gamma irradiation on growth and reproductive success of Daphnia magna

Aquatic invertebrates (water flea Daphnia magna) were exposed to low dose rates of external gamma radiation (from 0.4 to 31mGyh(-1)) over a 23-day period (i.e. 5 broods). Gamma radiation caused changes in neither survival nor somatic growth. Mass-specific respiration rate was significantly lower at 31mGyh(-1) than in the control. Reproduction was affected through early release and reduced size of broods after 15 days of exposure at 31mGyh(-1) (broods 3-5), resulting in a 21% fecundity decrease at 31mGyh(-1) compared to the control. A decreased resistance of neonates to starvation was observed in relation to dose rates. Possible mechanisms of gamma radiotoxicity for daphnid reproduction and implications for radioprotection are discussed.     

Optimizing the design of giant scallop (Placopecten magellanicus) spat collectors: field experiments

Field experiments were carried out in 1991 and 1992 in the Gulf of St. Lawrence (Québec, Canada) to examine the influence of various structural components of spat collectors on recruitment of the giant scallop (Placopecten magellanicus) and associated species. Components considered were monofilament diameter, heterogeneity (presence of knots), mesh size of external bags combined with monofilament density, and spatial arrangement of monofilament inside collectors. P. magellanicus spat were more abundant in collectors made with bags of intermediate mesh size (0.4x0.5 cm) containing low densities (2030 cm²) of monofilament than in other types of collectors. significant variations in spat numbers were, however, observed with other taxa such as Mytilidae, Hiatella arctica, Cerastoderma pinnulatum, Mya arenaria, Anomia simplex, Tellina sp., Veneridae, Dacrydium vitreum, Mactridae, Buccinidae, Littorina sp., Ostracoda and Foraminifera. Abundance of scallop spat did not vary significantly with spatial arrangement, diameter and heterogeneity of monofilament.Contribution to the program of GIROQ (Groupe Interuniversitaire de Recherches Océanographiques du Québec) and REPERE (Recherche sur le Pétoncle à des fins d'Élevage et de Repeuplement).     

Optimal patch time allocation for time-limited foragers

The Charnov Marginal Value Theorem (MVT) predicts the optimal foraging duration of animals exploiting patches of resources. The predictions of this model have been verified for various animal species. However, the model is based on several assumptions that are likely too simplistic. One of these assumptions is that animals are living forever (i.e., infinite horizon). Using a simple dynamic programming model, we tested the importance of this assumption by analysing the optimal strategy for time-limited foragers. We found that, for time-limited foragers, optimal patch residence times should be greater than those predicted from the classic, static MVT, and the deviation should increase when foragers are approaching the end of their life. These predictions were verified for females of the parasitoid Anaphes victus (Hymenoptera: Mymaridae) exploiting egg patches of its host, the carrot weevil Listronotus oregonensis (Coleoptera: Curculionidae). As predicted by the model, females indeed remained for a longer time on host patches when they approached the end of their life. Experimental results were finally analysed with a Cox regression model to identify the patch-leaving decision rules females used to behave according to the model’s predictions.